[Elecraft] Re: FM Broadcast Station Interference

[Dave Gingrich K9DC]

At 18:31 5/29/2002 -0400, you wrote:
>Again, thanks to everyone for all the postings and private communications re
>my RFI problem. Took the K2 about 20 miles up the coast to a more rural
>setting and tried the same test/conditions. With no connections to the K2
>except the gel cell/power cord everything was as quiet as a mouse. No
>evidence of RFI on any frequency.

FM-DC-AC comments aside, I still find it unusual that your K2 is plagued 
with this problem at all, especially from an FM station 6 miles away. 34 kw 
is not really a big FM signal. I live on the edge of the tower forest here 
with six 1000 foot towers in the neighborhood, five of them less than a 
mile away. Eight of the ten TV stations serving us and a dozen FM stations 
are on these sticks. At least two of the FM are 500kw smokers. Never an 
extraneous peep out of the K2.  [Now receiving anything on VHF is an 
entirely different situation, HI.]

Would it be possible for you to get another K2 owner to bring his radio to 
your shack and see if another rig has the same problem?  There are a lot of 
these rigs around, particularly in CA.  This technique worked for me when I 
was troubleshooting an AM broadcast interference problem on my K1 from a 
5kw station 2 miles away. It turned out the other K1 had the same problem 
at my station, so I turned to antenna mods, etc. (ended up elimiating it 
entirely by using an 80 meter horizontal loop, rather than an end fed wire).

But perhaps your problem is inside your radio, i.e. bad solder joint etc. 
Bringing another rig over would certainly let you know whether the problem 
was inside or outside the box.

I still puzzled how you could even tell. You identified the station, 
apparently heard rock music, but FM broadcast sigs modulation is +/- 75 KHz 
deviation. How could you even begin to detect that on anything inside a K2?

-Dave

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Dave Gingrich, K9DC - Indianapolis, Indiana  USA
K2 #2211, K1 #931, QRP-L #2376, ARS #1109,
FPQRP #389, IRLP #473, k9dc.ampr.org, CCIE #6748
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